It has been about a week since my OrdBot's first successful calibration print and it seems like a good time to write down some of my initial problems, experiences and solutions. However before I get into that a review of my 3D printer stack.

Electronics
AzteegX1 v1.0 (644P processor)
Lava heatbed, I have only used PLA at this point so this is still disconnected.Software
Mac OSX
Marlin firmware
Slic3r v0.9.9
Pronterface (March 2012 release)
Repetier-host Mac (0.56, lower versionthan linux/windows releases for some reason)

Now for the problems encountered during the past week, approximately in the order which I ran into them.

Pololu A4988 - I have used these before on my ShapeOko CNC machine. They have been so reliable that I completely forgot how to set them up, as such I blew up 3 drivers while setting up the electronics. So be careful, check the polarity and for the love of everything don't measure voltage when your multimeter is in continuity mode!

Leveling the bed - This was tedious but not particularly difficult. The LAVA heatbed has 8 M3 screws along the perimeter so calibration was just a matter of carefully tightening them until the height is just right. To measure the height I lowered the printer nozzle until it had just enough space for a piece of paper to slide underneath with little resistance, at this point I manually jogged the nozzle along the perimeter adjusting the M3 screws as necessary until the bed was level.

Setting the Z-Axis endstop - This step is ongoing and was very tedious without a way to precisely raise or lower the endstop actuator (a screw in sliding t-slot nut). I have it set fairly close, but still find myself hitting the "stop motor" button and manually turning the Z-Axis screws while the first layer is printing. Eventually I will print out something like this and dial in the Z endstop a more reliably.

Configuring steps per mm - This was the longest part of the process, and I'm still not sure why. Fortunately it wasn't difficult, just tedious. I know the steps per revolution on my motors (200), the microstep resolution for the steppers (16x), the pitch of MXL belts (2.032mm) and the number of teeth on the pulley (16). Using the equation on the buildlog.net configuration page gave me a number which ended up being way too small. My calibration object of choice was the nickel test thing on thingiverse, I just kept printing them out, measuring the insides and adding a ratio multiplier until satisfied that things were the correct size.

Pololu A4988 overheating - Once I had my machine calibrated I started trying to print larger objects that took more time. Without fail after 5-10 minutes after starting the machine would start losing steps. Eventually I noticed how hot the stepper drivers were and mounted a fan pointing at them which fixed the problem.

The notorious QU-BD MBE. This thing gave me a ton of trouble, so much so that I ordered a J-Head after the first day of trying to get it up and running. That said I've managed to get it to print very reliably and haven't yet felt the need to install the J-Head.

QU-BD pre-upgrades - Before I even had my printer assembled I performed some upgrades on the QU-BD. First is the QU-BD Modification Kit from the MakerSlide store. Secondly I hobbed the stock raptor gear with a small tap in my electric hand drill.

QU-BD overheating jam - There is a fan and heatsink on the extruder. I wired it (incorrectly) to the Azteeg X1 fan input, making it configurable in gcode (M106 and M107). My slic3r configuration toggled the fan on and off, so occasionally the cold-end of the extruder was heating up too much causing a jam. My current solution is disabling the cooling option in slic3r, but eventually I will wire the fan directly to the 12v input.

QU-BD underheating jam - My printer is in the kitchen and there is a nice crossdraft going through the room now that it is nice outside. The crossdraft was causing the nozzle to drop below 165 degrees, when this happens things usually jam. I need to wrap the hot end in some sort of insulation which will hopefully fix this problem.

QU-BD slicer jam - While printing the nautilus gear thing I was noticing frequent jams during the infill stage. The thing about this object was that there was very little amount of infill needed so the filament moved very slowly. My best guess is that the filament was sitting in one place so long that it heated up too high in the extruder which caused the jam. After reconfiguring slic3r to leave the object hollow there were no more jams on this print.

Pronterface vs. Repetier-host - This could probably be a blog post on its own. They both work but suffice to say that repetier-host is leaps and bounds ahead of pronterface in terms of usability. The one problem I had was that repetier-host allows you to configure the controller buffer size, the default is 63 which causes stuttering when printing complex surfaces with short line segments. I upped this value to 127 when I was 75% finished with the owl print (below) and you can tell just from looking at the surface of the model where I made that change because the surface quality improved dramatically. I just wish I had found that setting before printing all those feathers!

This owl is my longest print to date at 3 1/2 hours. This print was running while a draft was running past the printer, I probably fixed 5 or 6 jams while it printed which caused a several noticeable defects (most of them on the owls back).

After many attempts I finally got the Nautilus Gear to print. Now that everything is dialed in I could print one out in about an hour (~12 minutes for the two clips and ~18 minutes per gear).

I've been a fan of MakerSlide ever since building my ShapeOko CNC Mill, and have been interested in 3D printing since first hearing about the RepRap project in 2007. So when I first saw the OrdBot, I knew that it would be the printer I build. It didn't hurt that I had 10 feet of extra MakerSlide and a whole bunch of the special bearings and eccentric spacers left over from my ShapeOko build.

One of my goals was to build all the custom parts myself, the blue and black pieces in the photo above. Cutting aluminum on my new CNC machine pushed it to the limit, but worked out in the end. One of the larger OrdBot pieces is the handle, here is a shot of the ShapeOko making short work of it:

There are a couple parts that I modified or upgraded during the build. Most notably the Z axis. After reading about bent Z-rods I decided to get some ACME rods, and I wanted to use some spare Nema-23 motors that I had on hand.

The NEMA-23 motors for the Z axis were easy, I slightly modified the stock motor part to fit the new motor:

Attaching the ACME rod was a little trickier, but managed to hand fabricate a bracket with some 1/8" thick angle aluminum:

In the spirit of being thrifty, I signed up for one of the (now notorious) Qu-bd extruders during their kickstarter campaign. So far I've managed to get the extruder to work with a couple of simple motifications. Some more hand fabricated mounts and I had the extruder attached:

For the electronics I am using one of the first generation Azteeg X1 boards. So far I've been very happy with it (save for an exciting wiring mistake where I had the polarity backwards). I opted to run the wires through the hollow MakerSlide extrusions whenever possible. Here is the nearly completed wiring, I really appreciated the zip-tie holes:

After a few days of tweaking and calibrating, I'm getting some nice results. Here are some action shots with the machine up and running:

April of 2012 I signed up for the first batch of ShapeOko kits from inventables.com. Unsure of how popular the kit would be, inventables had a kickstarter-style order of 150 (or so) kits. That number was reached handily and several more batches followed. Since then the ShapeOko has become a standard item in their store.

I've wanted a CNC mill for a long time, but could never justify the expense. Now there are products like the MakerSlide linear rail system that made it possible for low cost machines. The first round of kits were only $200 for the entire mechanical platform - add your electronics and a dremel tool and the machine can start cutting.

So thats what I did.

The stock kit plus motors after assembly:

One of the nice things about the ShapeOko is how hackable it is. For instance if you want to make the cutting area larger you can just replace the MakerSlide with longer rails. So I added longer rails, a second Y-axis motor, a torsion box to mount everything on, a bigger router and some woodworking T-slot to hold work. Here is a picture of the machine a few weeks ago while cutting a large aluminum part for another project:

The current cost of the machine is $663.75, that includes all components bought for the machine regardless of whether or not they were used and shipping. So far I've spent another $150.55 on endmill of various sizes for for cutting various materials.

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About Me

Will Winder is a software developer. In his four years of study at UNH he took variety of advanced Computer Science courses including Object Oriented Design, Computer Networks, Artificial Intelligence and Compiler Design. He has been working professionally using C, C++ and Java since graduating in 2006. In his free time he continues to expand his skills by involving himself in many projects, some of which can be seen on this blog.